U.S. patent number 5,406,487 [Application Number 08/243,098] was granted by the patent office on 1995-04-11 for aircraft altitude approach control device.
Invention is credited to Peter G. Tanis.
United States Patent |
5,406,487 |
Tanis |
April 11, 1995 |
Aircraft altitude approach control device
Abstract
An improved aircraft altitude approach control device is
characterized by both visible and audible indications of changes in
the aircraft altitude as the aircraft descends to a landing. A
transducer is provided on the aircraft which produces an output
signal corresponding to the altitude of the aircraft. The output
signal is converted to a digital signal and then to an analog
voltage signal. A voltage controlled oscillator produces an audio
frequency signal whose pitch corresponds with altitude. A further
characteristic of the invention is the provision of a memory
circuit in which a digital signal corresponding to a preferred
landing is stored. This signal can be modified to produce a
preferred or reference analog voltage signal. The actual and
reference voltage signals are delivered to a glide slope meter
which indicates differences therebetween. Thus, a pilot can gauge
his landing approach relative to the reference or preferred landing
approach.
Inventors: |
Tanis; Peter G. (Glenwood,
MN) |
Family
ID: |
25103414 |
Appl.
No.: |
08/243,098 |
Filed: |
May 16, 1994 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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775129 |
Oct 11, 1991 |
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Current U.S.
Class: |
701/16; 701/15;
701/5; 701/8; 73/178T |
Current CPC
Class: |
G05D
1/0676 (20130101) |
Current International
Class: |
G05D
1/00 (20060101); G05D 1/06 (20060101); G08B
023/00 () |
Field of
Search: |
;364/427,428,433
;340/946,970 ;367/116 ;244/183 ;73/178T |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Chin; Gary
Assistant Examiner: Walder, Jr.; Stephen J.
Attorney, Agent or Firm: Burd; L. Paul Bartz; Richard O.
Gutenkauf; Robert W.
Parent Case Text
This application is a continuation of application Ser. No.
07/775,129, filed Oct. 11, 1991, now abandoned.
Claims
What is claimed is:
1. Apparatus for indicating to the pilot of an aircraft, the
altitude of the aircraft as it changes during a landing approach,
as compared to a desired altitude, by comparing the actual altitude
with an altitude recorded during a previously correctly executed
landing approach, and indicating deviations therefrom so that the
pilot can make adjustment in order to conform the landing approach
to the previously correctly executed approach, comprising:
(a) transducer means mounted on the aircraft for producing upon a
landing approach an electrical output signal corresponding to the
altitude of the aircraft relative to the ground;
(b) a first digital to analog converter connected to the transducer
means to produce an analog voltage representative of the altitude
sensed by the transducer means;
(c) memory means located in the aircraft;
(d) a series of digital voltage pulses stored on the memory means,
said series of pulses having been generated by recording the
digital voltage produced by a transducer during a previously
correctly executed landing approach on the same aircraft;
(e) a second digital to analog converter connected to the memory
means to retrieve the voltage signal from the memory means
representative of the previously correctly executed landing
approach;
(f) means for comparing the signals from the first digital analog
converter and the second digital to analog converter; and
(g) display means for displaying the difference between the two
signals to permit the pilot to make adjustment accordingly during
an actual landing approach.
2. Apparatus for indicating the altitude of an aircraft during a
landing approach, comprising:
(a) transducer means mounted on the aircraft for producing an
output signal corresponding to the altitude of the aircraft
relative to the ground;
(b) driver means comprising a counter connected with said
transducer means for producing a digital altitude signal from said
output signal;
(c) tone generator means connected with said driver means for
producing a variable audio tone corresponding with said digital
altitude signal, whereby a high pitch audio tone indicates a high
altitude and a low pitch indicates a low altitude of the aircraft
as the aircraft descends during landing;
(d) memory means connected with said tone generator means having
recorded thereon a series of digital pulses according to the rate
of change of altitude during a previous correctly executed landing
on the same aircraft, said series of digital pulses serving as a
reference; and
(e) means for comparing said series of reference digital pulses
with said digital altitude signal to produce a signal indicating
the difference between the actual aircraft altitude and the
preferred altitude of the previous correctly executed landing.
3. Apparatus as defined in claim 2, and further comprising
switching means for energizing said transducer means, driver means
and indication means when a flap setting lever and a throttle of
the aircraft are set for landing the aircraft.
4. Apparatus as defined in claim 2, wherein said tone generator
means includes
(a) a ripple counter for producing a series of digital voltage
pulses from said digital altitude signal in a given period
representing the altitude during that period; and
(b) a first digital to analog converter connected with said ripple
counter for converting said digital voltage pulses to an analog
voltage signal which varies over time.
5. Apparatus as defined in claim 4, and further comprising a
voltage controlled oscillator connected with said first digital to
analog converter for producing an audio frequency signal from said
analog voltage signal.
6. Apparatus as defined in claim 5, and further comprising means
for comparing a voltage signal from an actual landing with a
voltage signal corresponding with the altitude of a previous
correctly executed landing of the aircraft.
7. Apparatus as defined in claim 6, wherein said comparing means
comprises;
(1) a microprocessor controller connected with said ripple counter
for receiving a preferred sequence of digital voltage pulses
representing the altitude during a previous correctly executed
landing of the aircraft; and
(2) memory means connected with said microprocessor controller for
retaining said preferred sequence of digital pulses.
8. Apparatus as defined in claim 4, wherein said comparing means
comprises;
(1) a microprocessor controller connected with said ripple counter
for receiving a preferred sequence of digital voltage pulses
representing the altitude during a previous correctly executed
landing of the aircraft; and
(2) memory means connected with said microprocessor controller for
retaining said
preferred sequence of digital voltage pulses.
9. Apparatus as defined in claim 8, and further comprising a second
digital to analog converter connected with said memory means for
converting said preferred sequence of digital voltage pulses to a
preferred analog voltage signal.
10. Apparatus as defined in claim 9, wherein said comparing means
further comprises a glide slope meter connected with said first and
second digital to analog converters, respectively, for indicating
the difference between an actual landing analog voltage signal and
said preferred analog voltage signal.
11. Apparatus as defined in claim 2, and further comprising shock
absorbing means for mounting said transducer beneath a wing of the
aircraft, thereby to isolate said transducer from vibrations of the
aircraft.
12. Apparatus as defined in claim 11, wherein said shock absorbing
mounting means include a baffle connected with an aircraft wing and
shock absorbing material connecting said transducer with said
baffle.
13. Apparatus for indicating the altitude of an aircraft during a
landing approach, comprising:
(a) transducer means mounted on the aircraft for producing an
output signal corresponding to the altitude of the aircraft
relative to the ground;
(b) driver means comprising a counter connected with said
transducer means for producing a digital altitude signal from said
output signal;
(c) memory means connected with said counter and having recorded
thereon a series of digital pulses according to the rate of change
of altitude during a previous correctly executed landing on the
same aircraft, said series of digital pulses serving as a
reference; and
(d) means for comparing said series of reference digital pulses
with said digital altitude signal to produce a signal indicating
the difference between the actual aircraft altitude and the
preferred altitude of the previous correctly executed landing.
14. A method for indicating to a pilot of an aircraft the altitude
of the aircraft as it changes during a landing approach, comprising
of the steps of:
(a) storing a first series of digital voltage pulses generated
during a previously correctly executed landing approach of the
aircraft, and corresponding with the altitude of the aircraft;
(b) generating a second series of digital voltage pulses
corresponding with the actual altitude of the aircraft;
(c) comparing said first and second series of digital voltage
pulses to produce a signal representing the difference between the
actual aircraft altitude and the altitude of the aircraft during
said previously executed landing approach of the aircraft; and
(d) indicating to the pilot the difference between the previous and
the actual altitudes, whereby the pilot may take corrective action
to align the actual aircraft altitude during a landing approach
with the altitude of the previously executed landing approach.
15. A method as defined in claim 14, wherein said first series of
digital voltage pulses are stored in a memory for repeated
comparison on subsequent landing approaches.
16. A method as defined in claim 15, wherein said indicating step
comprises providing an audio indication of the difference between
the previous and actual altitudes.
17. A method as defined in claim 15, wherein said indicating step
comprises providing a visual indication of the difference between
the previous and actual altitudes.
Description
BACKGROUND OF THE INVENTION
Landing an aircraft is a very complex task. An experienced pilot
calls upon conditioned responses to rapidly changing occurrences
which are observed through sight, feel, hearing and kinesthesis.
There are many control options available to the pilot, each
affecting two or three variables. For example, if the pilot senses
that he is too high and applies forward pressure on the control
wheel, the aircraft will lower its nose, speed up, and move further
down the runway and may be too fast to accomplish the stall desired
for a good landing. The pilot must respond with coordinated use of
several of the controls available to him. To accomplish a good
landing, the pilot normally stabilizes as many of the variables as
he can and then deals with the remaining ones with coordinated use
of the controls.
Learning this complex operation is difficult for a student pilot,
often requiring many hours of training. One of the main problems is
learning how to observe the rapidly changing environment while
maintaining control of the aircraft. For example, when an aircraft
is landed, it must be "stalled" just as the wheels touch the
ground. The pilot must accurately judge this altitude by looking
out of the window while keeping the aircraft straight with the
runway. He can not be looking at his instrument panel, and if he
fixes his attention on one point, he will contact the ground at the
wrong time and bounce the aircraft. Many experienced pilots often
lapse into inattentiveness and make a poor landing.
Instrument pilots face the same problems in another environment.
They fly an instrument landing system to an elevation of 100 to 200
feet, at which point the pilot must see the runway. He must then
react to what he sees to correctly land the aircraft. Seaplane
pilots often make bad landings due to their inability to judge
height above smooth water.
BRIEF DESCRIPTION OF THE PRIOR ART
Automatic pilots have been developed which approximate a proper
landing. These are normally limited to large commercial aircraft
for several reasons including weight, complexity and cost. Auto
pilots are quite good at flying the instrument landing system part
of the approach. However, they do a poor job of the final landing
and pilots usually mistrust them. Large aircraft have a much higher
mass than typical light aircraft. Because of this they have more
inertia to continue in a straight line and have less tendency to
bounce if they contact the runway in a small rate of descent. Auto
pilots take advantage of this to approximate the proper landing
using a three stage approach. The first stage is flying the
instrument landing system (ILS). The second stage is a period
commonly referred to as "dead reckoning" following loss of the ILS
signal. In this stage, a computer approximates the previous flight
path and is updated with information from a radar altimeter. The
third stage begins when the aircraft comes within one wing span of
the ground and the control switches to a flare computer which
approximates the flare normally done by the human pilot.
These auto pilots flare and land typically in the following ways.
Some simply run the aircraft into the ground in a small but
positive rate of closure. Others bring the aircraft to level flight
just above the ground, allow it to slow and then drop onto the
ground. This uses a great amount of runway length so in response to
this, at some point in the "flare" the auto pilot is programmed to
pitch the nose down allowing the aircraft to run into the ground.
The flare computer determines a calculated flight path to produce
the desired results. Pilots normally prefer to fly the landing by
hand because it is difficult to take the aircraft away from an auto
pilot during the landing flare if it malfunctions.
The present invention was developed to overcome the drawbacks of
the prior auto pilot systems by providing an improved altitude
indicating device for a lightweight fixed wing aircraft which
informs the pilot of his altitude and rate of ground closure during
landing. This is done by providing audio and visual flare reference
with respect to a previous correctly executed landing.
SUMMARY OF THE INVENTION
The apparatus for indicating the altitude of an aircraft during a
landing approach according to the invention includes a transducer
which produces an output signal corresponding to the altitude of
the aircraft relative to the ground. A display driver and counter
are connected with the transducer for producing a digital altitude
signal from the transducer output signal. A digital LED display
device is connected with the display driver to indicate the
descending altitude of the aircraft as it lands.
An audio indication of the altitude of the aircraft is also
provided. In order to produce the audio output, a ripple counter, a
first digital to analog converter, and a voltage controlled
oscillator are provided. The ripple counter is connected with the
display driver and counter and produces a series of digital voltage
pulses in a given period representing the altitude during that
period. The first digital to analog converter is connected with the
ripple counter and converts the digital voltage pulses to an analog
voltage signal which varies over time. The voltage controlled
oscillator produces an audio frequency signal from the analog
voltage signal which is delivered to a speaker to produce an audio
output. A high pitch audio output indicates a high altitude and low
pitch audio output indicates a low altitude.
According to a more specific embodiment of the invention, a memory
is provided within which a sequence of digital voltage pulses
representing the altitude of a preferred landing descent for a
particular aircraft are stored according to a previous correctly
executed landing by a human pilot on the same aircraft. A second
digital analog converter is connected with the memory to convert
the preferred sequence of digital voltage pulses to a preferred
analog voltage signal. The preferred analog voltage signal and the
actual landing analog voltage signal are delivered to a glide slope
meter which indicates the difference between the signals to assist
a pilot in adjusting the aircraft to the preferred landing
descent.
According to another object of the invention, the transducer is
mounted beneath the wing of the aircraft using a baffle and
shock-absorbing material so that the transducer is isolated from
vibrations of the aircraft.
BRIEF DESCRIPTION OF THE FIGURES
Other objects and advantages of the invention will become apparent
from a study of the following specification when viewed in the
light of the accompanying drawing, in which:
FIG. 1 is a block diagram of the aircraft altitude approach control
tone generator circuit;
FIG. 2 is a block diagram of a preferred embodiment of the
invention including a glide slope meter for comparing an actual
landing with a preferred landing;
FIG. 3 is a block diagram of the power supply for the circuit of
FIG. 1;
FIG. 4 is a perspective view of the transducer mounting assembly
according to the invention;
FIG. 5 is a graphical illustration of a preferred landing analog
voltage signal plotted against time; and
FIG. 6 is a plan view of a control panel of the invention.
DETAILED DESCRIPTION
The apparatus for indicating the altitude of an aircraft during a
landing approach according to the invention will first be described
with reference to FIG. 1. As shown therein, the apparatus includes
a transducer 2 which is mounted on the aircraft. The transducer is
mounted on the underside of the wing of the aircraft just forward
of the wing flap so that it is arranged in an area where air flow
and its associated noise are at a minimum. This location thus
shields the transducer from the noise and air pressures generated
by air flow over the wing. As shown in FIG. 4, the transducer 2 is
preferably connected with the wing of the aircraft via a baffle 4.
The baffle replaces an inspection plate on the underside of the
wing just forward of the wing flap. The baffle is preferably
conically shaped, with the transducer mounted in the apex of the
cone on a shock-absorbing support 6. The location of the
transducer, and its baffle/shock-absorbing mounting arrangement
prevents the transducer from responding to noise and vibration
produced by the aircraft. It will be appreciated by those skilled
in the art that each particular type of aircraft will require a
differently shaped and mounted baffle assembly.
Referring once again to FIG. 1, the transducer 2 is of the
ultrasonic type which generates pulses to the ground and receives
echoes therefrom. The transducer produces an output in response to
the echoes which is a function of the distance from the transducer
to the ground. Thus, the output signal from the transducer
corresponds to the altitude of the aircraft relative to the ground.
The output signals are delivered to a range finder circuit board 8
which processes the output signals from the transducer so that they
correlate to the altitude of the aircraft. A display driver board
10 including a binary counter 12 is connected with the range finder
circuit board and produces a digital altitude signal corresponding
to the output signals from the transducer. A visual indication of
the instantaneous aircraft altitude as provided on a digital LED
display 14 connected with the display driver circuit board 10. The
digital display is mounted at a location in the aircraft where it
can be seen by the pilot.
A characterizing feature of the invention is that an audio output
signal is also generated which corresponds with the aircraft
altitude and which varies as the aircraft makes a landing. More
particularly, a tone generator circuit board 16 is connected with
the display driver board 10 for generating an audio signal
corresponding with the digital altitude signal produced by the
display driver board. The tone generator board 16 includes a buffer
18 connected with the binary counter 12 of the display driver
board. A ripple counter 20 is connected with the output of the
buffer. The ripple counter produces a series of digital voltage
pulses for a given period of time representing the altitude of the
aircraft during that period. A first digital to analog converter 22
is connected with the ripple counter and converts the digital
voltage pulse to an analog voltage signal which varies over time.
The analog voltage signal is amplified by operational amplifiers
24, 26 and delivered to a voltage controlled oscillator 28 which
produces an audio frequency signal from the analog voltage signal.
The audio frequency signal is amplified by a further operational
amplifier 30 and adjusted via a rheostat 32 in order to match the
input impedance of the aircraft audio amplifier 34. The audio
frequency signal is then provided to an audio speaker such as the
headset 36 so that an audio output is produced which can be heard
by the pilot. A high pitch audio output corresponds with high
altitude of the aircraft and a low pitch audio output indicates a
low altitude. Thus, the audio output varies as the aircraft
descends during the landing thereof.
Referring now to FIG. 2, a preferred embodiment of the invention
will be described. In the preferred embodiment, a memory circuit is
connected with the tone generator board 16 in order to record the
rate of change of altitude when a proper, landing is made by an
experienced pilot for that particular aircraft. A signal
representing the aircraft altitude is taken from the output of the
ripple counter 20 and delivered to a microprocessor controller 38
in digital form. This data is formed into 8-bit words and sent to
an address control circuit 40 via a data bus 42. The address
control circuit 40 assigns a location in an 8K memory chip 44 and
transfers the data thereto via data bus 46. This stored data
represents the altitude versus time of a properly executed landing.
The series of digital voltage pulses representing the altitude
during a preferred landing descent can either be pre-programmed
into the memory 44 or recorded therein based upon an actual landing
performed by an experienced pilot, where the actual landing
corresponds to a preferred or "perfect" landing approach.
The stored information corresponding to a preferred landing can be
recalled from, the memory for comparison with an actual landing in
the following manner. The data stored in the memory is delivered to
a second digital to analog converter 48 via a data bus 50 under
control of the microprocessor controller 38. The second digital to
analog converter produces a preferred analog voltage signal
corresponding with the preferred sequence of digital voltage pulses
stored in the memory. The preferred analog voltage signal is
amplified by an operational amplifier 51 and delivered to a glide
slope meter 52. The glide slope meter 52 also receives the actual
landing analog voltage signal from the first digital to analog
converter 22 (which is amplified by the operational amplifier 24)
and compares the voltage signals. The difference between the actual
landing analog voltage signal and the preferred landing analog
voltage signal is indicated on the glide slope meter 52, thereby to
indicate to the pilot whether he is above or below the preferred
landing altitude.
There is shown in FIG. 5 a graphical representation of the
preferred analog voltage signal generated by the second digital to
analog converter. As shown therein, the voltage decreases over
time, which corresponds with the decreasing altitude of the
aircraft as it makes its landing. The voltage shown in FIG. 5 is
the standard voltage to produce a proper glide path. The actual
landing approach in progress also produces voltage at the output of
the first digital to analog converter 22. The two voltages are
placed across the standard glide slope indicator meter. If the
voltages are the same, the glide path is the same as the preferred
reference glide path and the meter will remain at zero for the on
glide path indication. If the aircraft is above the referenced
glide path, the actual voltage will be higher causing the meter to
deflect below the zero position and provide a "fly down"
indication. If the aircraft is below the referenced glide path, the
reference voltage will be higher than the actual voltage and the
meter will deflect above the zero position giving the pilot a "fly
up" indication. Although not shown in the drawing, the glide slope
meter also includes other wires for connection with the glide slope
receiver (which is a part of the instrument landing system) and
connections for auto pilot coupling.
There is shown in FIG. 3 the power supply circuitry for the
altitude indicating device according to the invention. The tone
generator board 16 is connected with a power supply circuit board
54 which produces 6 and 12 volt outputs. The power supply board 54
is connected with the electrical system of the aircraft 56 via two
microswitches 58, 60 connected with the flap and throttle controls
62, 64, respectively. The microswitches energize the power supply
board and thus the aircraft altitude approach control system so
that it will operate only when the aircraft controls are in a
position used for landing. When the aircraft is in the landing
configuration (i.e., when the flaps and throttle are set for
landing), the system is energized. The useful range of the
invention is from zero feet to 35 feet, but the system can be
modified to operate at altitudes up to 70 feet.
There is shown in FIG. 6 a control panel, which is accessible to
the pilot of the aircraft, for controlling the operation of the
aircraft altitude indicating device. The control panel 66 includes
an on/off switch which controls the operation of the
micro-processor controller 38. A selection switch 70 is operable to
control the functional operation of the invention. It has settings
to place the memory 44 in the record mode, whereby the digital
voltage pulses produced during an actual landing are recorded in
the memory. The switch 70 also includes a compare mode which
controls the delivery of the signals from the memory and from the
first digital to analog converter to compare an actual landing with
a preferred landing. Finally, there is an audio setting for the
switch 70 whereby the invention can be used to produce the audio
output from the tone generator board via the headset 36. The panel
66 also includes the digital LED display 14.
In accordance with the invention, a pilot can guide his aircraft
during landing thereof with respect to a preferred landing descent
stored in the memory. This enables the pilot to imitate a preferred
landing even though he might not be able to see the ground. The
glide slope meter is commonly coupled to the auto pilot system of
the aircraft in order to control the aircraft pitch. In this case,
a coupled auto pilot approach could be flown all the way to
touchdown. The memory of the invention can be programmed by other
sensors of parameters that are significant to the approach and
landing such as air speed, power setting, distance, and ground
speed.
The initiation of the altitude approach control device preferably
begins either at a preset altitude when the recorded and measured
voltages corresponding to the altitude are the same, or when the
instrument landing system glide slope becomes unreliable if an
instrument landing system was in progress as determined by rapid
deflection of the glide slope needle.
While in accordance with the provisions of patent statute the
preferred forms and embodiments of the invention have been
illustrated and described, it will be apparent to those of ordinary
skill in the art the various changes may be made without deviating
from the inventive concept set forth above. For example, the
present invention is suitable for use with a radar altimeter and
could easily be incorporated therein.
* * * * *